Toys may be used for a number of educational purposes. Some toys have incidental educational value, while others are known specifically by the moniker of "educational toys." Educational toys are typically built for and used by young children. One could make the argument that an educational toy is actually any toy. Most children are constantly interacting with and learning about the world. This definition is ultimately too broad because one could make the same argument about a rock or a stick as it is not uncommon to see a child play with almost anything nearby.
The difference lies in the child's perception or reality of the toy's value. An educational toy should educate. It should instruct, promote intellectuality, emotional or physical development. An educational toy can teach a child about a particular subject or can help a child develop a particular skill. The key difference is the child's learning and development associated with interacting with the toy.